Tube bending machine with mechanism for control of wall thickness actuated by the rotatable bending die in accordance with its speed of rotation



' 2,810,422 TUBE BENDING MACHINE WITH MECHANISM FOR CONTROL oF WALL B. F. BOWER Oct. 22, 1957 THICKNESS ACTUATED BY THE ROTATABLE' BENDING DIE IN ACCORDANCE WITH ITS SPEED 0F ROTATION 7 Sheeizs-Sheei'l 1 Filed April '7. 1954 mm mm BYRON F. Bowie Oct. 22, 1957 B. F. BowER TUBE BENDING MACHINE WITH MECHANISM FOR CONTROL OF WALL THICKNESS ACTUATED BY THE ROTATABLE BENDING DIE IN ACCORDANCE WITH ITS SPEED OF ROTATION 7 Sheets-Sheet 2 Filed April 7. 1954 BYRON F. BOWEQ www.

0t 22, 1957 B. F. BowER 2,810,422

TUBE BENDING MACHINE WITH MECHANISM FOR CONTROL 0F WALL THICKNESS ACTUATED BY THE ROTATABLE BENDING DIE IN ACCORDANCE WITH ITS SPEED OF ROTATION Filed April 7. 1954 7 Sheets-Sheet 3 BYRON F. Bom/Ee Oct. 22, 1957 B. F. Bowr-:R 2,810,422

TUBE BENDING MACHINE WITH MECHANISM FOR CONTROL 0F WALL THICKNESS ACTUATED BY THE RoTATABLE-BENDING DIE IN ACCORDANCE WITH ITS SPEED 0F RoTATIoN Filed April '7, 1954 '7 Sheets-Sheet 4 ,616 ,ago T5/zz Il? 118 l l I u BYeo/v F. Bo'wEe Oct. 22, 1957 B. F. BowER 2,810,422

TUBE BENOLNG MACHINE wml MECHANISM FOR CONTROL OF wALL THICKNESS ACTUATED BY THE ROTATBLE BENDING DIE IN ACCORDANCE WITH ITS SPEED OF ROTATION Filed April fr. 1954 y '1 sheets-sheet 5 169 A 169 171 L 191 185 A 1 f77 Egj -g. 13

167 18a ,68 A 18V/64 lk i N V58 16.3, 17g/ily B NEW NO2/VAL El TEAVEL TRAVEL Oct. 22, 1957 B. F; BowER 2,810,422

TUBE BENDING MACHINE WITH MECHANISM F'OR CONTROL 0F WALL THICKNESS ACTUATED BY THE ROTATABLE BENDING DIE IN ACCORDANCE WITH ITS SPEED OF ROTATION Filed April 7. 1954 7 Sheets-Sheet 6 Il -UZETZ Z Dr' @Yeo/v F BoWE/a wf En-Z;

B. F. Bowl-:R 2,810,422 TUBE BENDING MACHINE WITH MECHANISM FOR CONTROL OF WALL Oct. 22, 1957 THICKNESS ACTUATED" BY THE ROTATABLE BENDING DIE IN ACCORDANCE WITH ITS SPEED v0F' ROTATION Filed April 7. 1954 '7 Sheets-Sheet 7 TUBE BENDING MACHINE WlTH MECHANISM FOR CNTROL OF WALL THICKNESS ACTU- ATED BY THE ROTATABLE BENDING DIE IN ACCORDANCE WITH ITS SPEED F RTA'HON Bryon F. Bower, Aurora, Ill., assigner to Pines Engineering Co., Inc., Aurora, Ill., a corporation of Illinois Application April 7, 1954, Serial No. 421,506

8 Claims. (Cl. 153-40) The present invention relates to tube bending machines and is more particularly directed to means for improving the bending operation so as to make it possible even in relatively thin walled tubing to substantially maintain the original wall thickness in the outer walls of the bends.

In the bending of tubing in accordance with my invention the tubing is usually bent around a bending die, a clamp block being used to hold the advancing end of the tubing against the bending die. In addition, a pressure die presses the tube snugly against the bending die. Preferably, a mandrel is placed inside the tube and is advanced to the proper position for bending, which is with its rounded tip at the tangent line of bend. Bending takes place when the clamp block and bending die start to turn about the axis of the bending die. When properly positioned, the mandrel does not advance after the bending die is under way.

As the bending die is rotated, the tube is drawn along with it and the pressure die does the actual bending of the tube against the approaching surface of the bending die.

It will be appreciated that in a bending operation of this type the wall of the tube on the outside of the bend is subjected to a terric tension and this tension increases as the radius of the bend is made smaller. Not only is the outer wall subjected to bending stresses but also to the force necessary to pull the tubing around the bending die. As a result, the tubing is weakened by a stretching or thinning of the outer wall with an increased possibility of failures.

It is an important object of the present invention to provide an improved tube bending means wherebyvthe wall thickness of the tube is substantially maintained throughout the outer wall of the bend or is reduced to a desired predetermined thickness.

Another object of this invention is to provide tube bending means whereby the thickness of metal in the tubing wall is controlled and a better all around strength is obtained in the bent portion of the tubing; l

In my Patent No. 2,357,873, issuedSeptember 12, 1944, means are provided for pushing the tubing as it is being drawn by the bending die so as to relievethe tubing itself of a substantial portion of the strain .necessary to draw the tubing around the die. This pushing of the tubing is carried out in such a fashion as to eliminate the drag of the tubing so that the principal strain placed on the tubing is that necessary to bend it. This means, of course, that the metal in the outer half of the tubing bend will be stretched to the amount necessary to provide the additional length at the outside of the bend. Although this avoids some of the reduction in cross-section of the tubing wall, there still exists a weakening of the metal at the bend thereby making it the weakest portion. of the nished tubing. This is true in the operation of all bending machines of the same type.

Normally when a tube is bent over a bending die, the tube travels toward the die at a speed approximately 2,810,422 Patented Oct. 22, 1957 f. @CC

equivalent to the speed at which the bend is formed at its centerline, commonly known as its neutral axis. When bending occurs, the inside Wall of the bend is formed at a speed lower than at either the neutral axis or the outside wall, the speeds being in direction proportion to the respective radii at the bend. It follows that a thickening of the inside Wall of the bend and a thinning of the outside Wall thereof are also in direct proportion to their respective radii. Accordingly, if the travel of the tubetoward the bending die is increased to equal the forming of the bend aty the outside wall, the original thickness of the tube will be maintained substantially along the outer wall of the bend.

In mypresent invention, there is provided means for so controlling the pushing vpressure applied to the tube as to effect a rate of travel necessary in maintaining the thickness of the outer wall of the bend. This control feature is accomplished through a valve so connected operatively to the bending mechanism as to translate rotary movement of the bending die intoy pushing pressure required on the tube.

Other and more detailed objects and advantages of the invention will appear more fully in the following description, reference being made to the accompanying drawings inv which preferred forms of the invention are shown. It is to be understood, however, that the drawings andthe description are illustrative only and the invention disclosed therein is limited only by the claims.

Iny the drawings:

Figure 1 is a plan View of a tube bending machine embodying my invention;

Figure 2 is a side view in elevation of the bending machine shown in Figure l;

Figure 3 is an enlarged fragmentary vertical cross* sectionalV view taken along the line 3 3 of Figure 1 and illustrating details of construction of a pressure die roller, a bending die, and associated mechanism;

Figure 4 is an enlarged end view in elevation of the machine showing the relation of parts with theclamping die in an open position;

Figure 5 is an enlarged fragmentary vertical crosssectional view, taken along the line 5-5 of Figure 4, showing details of construction of certain of the relatively movable parts of the clamping die mechanism;

Figure 6k is a view, similar to Figure 4, showing the tubing in clamped position;

Figure 7 is an enlarged plan view in elevation, Vembodying certain elements of the die mechanisms, illustrating a completed bending operation and the relative position of the mandrel; Y

Figure 8 is a diagrammatic view illustrating the control apparatus by which the several operations are carried` out in a tube bending operation;

Figure 9 is an enlarged vertical cross-sectional view in elevation of the directional valve, with parts in neutral position, shown in Figure 8;

Figure l0 is a fragmentary cross-sectional view, Vwith parts in elevation, showing details of construction of the actuating handle connection to the spool of the directional valve of Figure 9;

Figure ll is a fragmentary cross-sectional View, With parts in elevation, showing details of construction of the linkage connecting the foot of the actuating handle and the body of the directional valve of Figure 9;

Figure l2 is a reduced View of the directional valve of Figure 9 showing the operative relation of parts when the valve spool is moved to the left;

Figure 13 is a view similar to Figure 12 showingY the valve spool moved to the right;

Figure 14 is an enlarged vertical cross-sectional View in elevation of the offset tracing or following Valve shown in Figure 8 and with parts in a normal operating position; Figure is a similar View of the valve of Figure 14 showing the operative relation of parts when the valve spool has been moved to the left placing the valve in a neutral or non-operating position;

Figure 16 is a View, similar to Figure l5, showing the operative relation of parts when the valve is in an operating position the reverse of that shown in Figure 14; Figure 17 is an enlarged View in elevation of a tube bend, with the associated clamping and pressure die mechanisms shown in dotted lines, and illustrating the various bend radii and distances of tube travel in accomplishing a bend by the machine of this invention;

Figure 18 is a view diagrammatically illustrating a modified form of bending controlmechanism;

Figure 19 is a side view in elevation of the tube gripping member of the pressure dieY shown in VFigure 18;

Figure 20 is a front view in elevation of the tube gripping member showing the serrated gripping face; and,

Figure 21 is a view diagrammatically` illustrating a second modified form ofbending control mechanism.

Referring now indetail to the drawings, my invention is shown as embodied in a tube bending machine wherein the numeral 36 representsthe base ofthe machine and the numeral 31 is the frame thereof. At one end of the frame 31 there is mounted for rotation a bending die supporting head 32 uponwhich a bending die 33 is removably mounted. The supporting head also carries with it a frame work 34 that supports a clamping die mechanism 3S for clamping the end of a piece of tubing to the bending die 33. The framework 34 also supports an operating cylinder 36 that is adapted to close the clamping die mechanism 35 against the corresponding portion of the bending die.

As best shown in Figure 5, the frame 34 has a guide 37 for slidably receiving therein a clamping die actuator 38. An inverted T-slot 39 in the upper side extends along the actuator and terminates short of the outer end thereof in which an adjusting screw 46 is threaded. An adjusting block 4l has depending from` its forward end a slide portion 42 seated within the slot 39 and engaged by the screw 40. A spacer block 43, inserted between the adjusting block 41 and a clamping die 44, is of a vlength to properly position the Vdie at a predetermined distance from the bending die 33 when in an open position as shown in Figure 4. A spacer of shorter or longer length may be inserted to accommodate tubing of a diameterl different than shown. The necessary adjustment of the die 4dto insure closing on an inserted -length of tubing 45 '(Figure 6) is effected through the screw 40. When adjusted, the block d3 and the die 44 are clamped to the actuator 38 by means of clamp boltsV 46, 46 each of which have a head 47 slidable within the slot 39 and a nut 48 for locking the bolt in place.

A pressure die mechanism 49 guides the forward move- Vment of the tubing and cooperates with the bending die 33 to bend the tubing as the die is rotated. A frame 50, carried by the machine frame 31 and having spaced side members 51 and 52, has a guide 53 for slidably receiving therein a pressure die actuator 54. An adjusting screw 55 permits adjustment of a roller support 56 in the guide to position rollers 57, 58 and 59 in tube engaging positions. When adjusted, the support is locked by clamp bolts 6b, 60 to the actuator 54 in a manner similar to the locking of the clamp bolts 46, 46. Each of the rollers has a circumferentially extending semicircular tube receiving slot, similar to a slot 61 in the roller 57. As shown in Figure 3, the roller support 56 is bifurcated at its forward end to provide upper and lower plates 62 and 63 between which the rollers are carried by mounting pins, only pin 64 being shown for roller 57. it will be noted that roller 5'7 is positioned in diametric alignment with the rounded end of bending die 33 for a purpose to be more fully defined hereinafter. The rollers 58 and 59, spaced laterally of the roller 57, engage and freely guide the tubing 45 in its forward movement during the bending operation. The pressure die mechanism is adapted, when properly adjusted, to move the rollers into and out of engagement with the tubing by means of a cylinder 65 having a piston rod 66 connected by a set of links and pins indicated generally at 67 in Figure 2. The cylinder 65, as well as the cylinder 36 which operates the clamping die mechanism 35, is supplied with a suitable uid under pressure (either liquid or air). The details of the control of this mechanism form no part of this invention and therefor such details have not been shown.

Tubing to be bent is placed over a mandrel 68 that has its end rounded as indicated at 69 (see Figure 7). This mandrel is supported upon a mandrel actuating rod 70 which is threaded into the mandrel as indicated at '71. A number of types of mandrel mountings may be employed one of which is shown in my Patent No. 2,357,873. In the arrangement therein, provision is made for an operatingrcylinderV and a piston connected to the mandrel actuating rod. The actuating rod is of such length that, when the piston is advanced, the rounded tip 69 of the mandrel is at the proper position for bending the tube which is in diametric alignment with the rounded end of the bending die 33 and the pressure die roller 57. As the details of the Vactuating rod and the mechanism for its advancement form no part of this invention, they have not been shown.

. The normal operation of a bending machine, such as has just been described comprises a sequence of operationsas follows: first, the tubing 45 is placed over the mandrel and set into a tube receiving groove 72 of the bending die 33. The clamping die 44 is next caused to close with its tube receiving groove 73 against the tubing to clamp the .same against the bending die. Actuation of the clamping die is effected through the operating cylinder 36 from which extends a piston rod 74 connected to the clamping die actuator 38 by means of a set of links and pins generally indicated at 75 and which ex- `down throughthe frame (Figure 4). The bending die and the clamping die mechanism 35, as they rotate with vthe shaft, pull the tubing around the axis of the bending die. YThe rollers 57, 5.8 and 59. prevent the rearwardly extending part of the tubing fromswinging'so that the tubing actually is bent by the roller 57. The tubing 45, as it is drawn aroundthe bending die, isrsubjected to a terrific strain, particularly at the point where it is being bent and pulled around the nose of the mandrel. The rounded mandrel nose isnecessary to prevent the tube from flattening Vunder this strain in order to reduce the distance around the curve and thus reducev the amount that the metal must stretc lt has been found that the strain placed on the tubing not only weakens the metal but practically limits the sharpness of thel bend that can be given to tubing by drawing it around a bending die. However, I have developed mechanism whereby it is possible not only to eliminate practically all of the strain to which the tubing is subjected and thus get sharper bends by means' of a bending die operated in the manner previously described, but also to maintain substantially the thickness of the unbent tubing around the outside of the bend thereby retaining all` of the original strength of the tubing.

Inaccordance with the principles of the present inventionthe tubing is pushed forward toward the bending die asit ,is being drawn thereby soras to relievethe tubing itself of the strain necessary to draw the tubing around thedie. This pushing of the tubing is carried out at that pressure necessary to eliminate 'both the strain of drawlingithe tubing and the stretching thereof-to provide `the lcontact between the tubing and the rounded nose of the `bending die or, stated in` another way, the line ofcontact at thediametrical axes of the roundednose of -the bending die andY the adjacent roller 57. With' metal in a llnid state within the small working area, any pressure exerted axially lengthwise. of the tubing will be. effective at and confined to that working area. Consequently, the rounded nose of the. mandrel need only to prevent a collapse of theuid metal rather than to resist a drawing strain. Also, because fluidity of the metal is conlined to such a small working area, thepressure exerted axially on'the tube,.if controlled, will not eect aforward bending at the tangent of the bend. In Figure. 17, the narrow working area is identified by the'numeral 79.

As shown, the distance from point A (intersection of the neutral axis of the tubing with the aligned diametrical axes of the bending die 33 and the pressure die roller 57 at the end of the bend.) to point B (intersection. of the neutral axis of the tubing with. the diametrical axes of the bending die 33 at the start of the bend) is shown by the line of normal travel D-E onA therearward straight section of the tubing. Duringthis travel in the-normal bending of a tube, the length along the inside'of the bend is less than along the neutral axis and the vlength along the outside of the bend is greater. than along Athe neutral axis. As a result, the wall on'the inside of the tubing bend is subjected to compression and thethickness increases while the wall on the outside ofzthe tubingbend is subjected to tension and the thickness decreases. The dierence in length along the neutral axis and along the outside of the tubing bend is identified by the distance E-C. If sufcient pressure is exterted at Py in a direction axially lengthwise of the tubing to elect a movement of the tubing from D to C instead of from` D .toE during the complete bending operation, then suicient metal will be available at the working area 79 to avoid a stretching or thinning of the wall thickness along the outside of the tubing bend. This has the apparent mathematical effect of moving the neutral axis from the center of the tubing to the outside thereof. Clearly, by increasing both the compression on the inside wall of the tubing bend and its thickness, the strength of the tubing will be'enhanced. at that area. Similarly, by eliminating both the stretching of the outside wall of the tubing bend anda reduction of its thickness, the original strength ofthe tubing will be maintained at that area.

In the bending of tubing without pressure being exerted in a direction axially lengthwise of the tubing toward. the

bending die, the following proportions determine theV thickness of the inside and the outsidewalls ofthe bend.

E511 T1 R T=wall thickness of unbent tubing T1=thickness of outside wall of bend R--radius of neutral axis at bend R1=radius of outside wall of bend T E T2- R T 2=thickness of inside wall of bend R2=radius of bending die groove and inside wall of bend.

Assuming that tubing 45 is 2 inches in diameter, that the radius of the tube receiving groove onthe rounded nose of the bending die is 1f', and that the wallthickness of the unbent tubing is .10", then from the foregoingin thickness lor 331/3 T1=.10-and `the thickness Vof theunbent tubinghas been maintainedin the outside wall of the bend.

At the same.time- T2,=.3o" or the thicknessef the inside. wan ofthe bend has been trebled..

Accordingly, there is provided herein mechanism by which to effect the movement'of the neutral axis of the tubing to the outside wall ofthe bend and to exert pressure against the tubing to move the tubing to the bending die a distance equal to the length ofthe outside wall 'of the bend. Y Y

In Figure 3, the bending die 33 is shown as being provided-with' an upwardly extending boss 80 having areduced end 81 for mounting a control drum 82. A nut 83, on the end of shaft 78 extendinglthrough the assembly, serves to hold the shaft in 'a depending position. The drum and the bending die co-rotate on a common axis for a purpose to be more fully explained later.

It is to be noted that the peripheryrof the drum is vin alignment with the outer wall of the tubing 45 when seated in the bending die. In other words, the radius of the drum is vequal to the distance from the outside ofv the tubing 45 to the longitudinal axisof` the shaft 78 on. which both the bending die 33 and thedrumI are mounted.

As best shown in Figures 1 and 2, a pusher cylinder base 84 is mounted on the machine frame 31 for forward orlateral adjustment. A pair of aligned pusher cylinders 85 and 86, shown in vertical relation to each other, are carried by a frame 87 mounted on the base. The cylinder 85,-with a piston 88 anda forwardly extending piston rod 8,9, is adapted. to operate when supplied with a suitable fluid underpressuref. Similarly, the cylinder S6 has .a piston 90 and a forwardly extending` piston rod 91.

AnV L-shaped bracket 92, mounted on the frame 87, supports an idler drum carrier 93 by means of a stud 94. An idler drum 95, carried by the carrier 93,` is operatively connected to the control drum 82 by means ofan'endless tape 96 applied around the drums.

Located between the pusher cylinders and thebending mechanism is a tubingclamp structurey 97. A raised member 98 on the machine frame 31 vcarries a slidable base 99 on which there is `mounted a clamp structure frame 100. Bosses 101 and 102 extend fromrthe rear of the frame and receive, respectively, thethreaded connecting ends 103 and 104 of the piston rods 89 and 91. The tubing -clamp structure 97, acting as acrosshead, is thereby actuated along the member 98. by `the pusher cylinders.

A cylinder 105, pivotally mounted as indicated at. 106 between frame side members 107 and 108, is Vactuated when supplied with a suitable fluidunder pressure. piston 109 has a piston rod 110 pivotally connected through ablock 111 to a wedge-shaped clampmember 112. The piston actuates the clamp memberralong a sloping surface 113 whereby the groove 114 in the clamp member seats against the tubing inserted through the opening 115. The wedging action thereby locks the tubing in the tubing clamp`structure 97.

A dove-tailed guide bar 116 on the clamp structure frame has a tracer or follower valve117 mounted for adjustment along its length. At the forward end of the valve is a tracer nger or sensing arm 118 adapted to contact a dag member 119 mounted to slide along the tape 96 and with a locking screw 120 to clamp it in adjusted position.

In Figure 4 is illustrated the mechanism through which the bending die 33iis'rotated. The shaft 78 extends downwardly through the machine frame 31 and has mounting sleeves 121 antl1122 locked thereon by a key 123. At the upper end of the sleeve 121 is mounted a roller bearing e124., It -will be noted that the sleeve tapers downwardly to receive a chain drive sprocket 125 which is locked against relative rotationby a key 126` A pair of lock nuts 127 Aand 128 on the sleeve 122 are operable to adjust the sprocket vertically on the sleeve 121. Another roller bearing 129, mounted in the machine frame 31, embraces the sleeve 121. A sleeve 130 carries a support arm 131 and extends and is fastened to the side member 76 by means of bolts 132 and 133. The sleeve 130 is retained on the sleeve 121 by a lock nut 134.

Transversely spaced, parallel supports 134a project rearwardly from the end of the machine opposite the bending mechanism and extend beyond the base 30 of the machine and have a web 13511 transversely connected between their lower edges. Vertically spaced, transverse supports 137 and 138 extend betweenthe supports 134a and carry a pin 136 on which a chain idler sprocket 135 is journalled. The idler sprocket is mounted in horizontal alignment with the drive sprocket 125.

Between the sprockets and mounted on the machine frame 31, by means of hangers 139 and 140, is a bending cylinder 141. A piston 142, within the cylinder, has a forward piston rod 143 and a rear piston rod 144. A connector 145 is threaded or otherwise secured to the end of the forward piston rod and a similar connector 146 is secured to the other or rear piston rod. A roller chain 147, with the ends secured to the connectors 145 and 146, is mounted around the sprockets '125 and 135.

The cylinder is arranged to operate when supplied with a suitable fluid under pressure. The piston moves to the right (Figures 1 and 2) to effect an operation of the bending mechanism and moves to the left to return the mechanism to its original position. It will be noted that the piston rods 143 and 144 are of different diameters. As the piston rod 143 is relatively small in diameter, a maximum of piston area is exposed to iluid pressure during the bending cycle. C0nversely,`the piston rod 144 being of larger diameter reduces the piston area exposed to uid pressure thereby electing a quick return of the bending mechanism to starting position. Details oi' the control of the bending Cylinder mechanism form no part of the present invention and therefor such details have not been shown.

.Reference is now made to `Figure 8 ofthe drawings wherein there is diagrammatically illustrated the general system of controls for the tubing clamp structure and the pusher cylinders. A motor 148, which is mounted on the underfside of the web portion 135:1 drives a pump A149 that draws fluid, preferably a liquid such as oil, from a reservoir 150 through a suction line 151. The Huid is then pumped through a conduit line 152 to a directional valve 153. This system is'intended to operate at a predetermined pressure and when the pressure4 is exceeded'sutlcient fluid is bled through apressure reliefrvalve V154 and b`y-passed through a Vconduit --8 155 back to the reservoir to maintain the operating' pressure.

Details of'construction ofthe directional valve 153 are best shown in Figures 9 to 13 inclusive. The valve has a body 156 axially chambered as at 157 to slidingly receive therein a spool 158. Both ends of the chambered body are closed by threaded plugs 159 and 160. The plug 160 is provided with an opening 161 through which extends an actuating rod 162 from the spool. Valve lands 163 and 164 are intermediately spaced on the body of the spool. An abutment member 165 extends outwardly from the valve land 163 and a similar abutment member 166 connnects the valve land 164 and the actuating rod 162. It will be noted that the abutment member 166 is larger in diameter than the actuating rod for a purpose to be more apparent later.

Spaced ports 167 and 168 are located at one side of the valve body 156 and are positioned intermediately relative to spaced ports 169, 170 and V171 at the opposite side of the body. With the spool 158 moved to the position shown in Figure 9, the lands 163 and 164, respectively, cover the ports 167 and 168 and are positioned intermediately of the ports 169, 170 and 171. In this relation of parts, the valve 153 is in a neutral or inoperative condition.

In order to move the spool to render the valve operative, an actuating handle mechanism 172 is provided. The free end of the actuating rod 162 is bifurcated having sides 173 and 174 between which an actuating handle 175 is intermediately connected by a pivot 176. At its lower end 177, the handle is bifurcated to embrace an end 178 of reduced width of a link 179 and is rockably connected thereto by a pivot 180. The opposite end 181 ofthe link, similar to end 178, is connected by means of a pivot 182 to and between sides 183 and 184 of a bifurcated extension 185 of the valve body 156. A ball shaped upper end 186 of the actuating handle facilitates being grasped by an operator.

Figure 12 shows the relation of parts when the actuating handle has been swung toward the valve, as shown by the arrow. It will be noted that the spool abutment memberv165 is seated against the end plug 159. The resulting position of the spool locates the valve land 163 between the ports 167 and 169 and the valve land 164 between the ports 168 and 170.

Figure 13 shows the relation of parts when the actuating handle has been swung away from the valve in a direction shown by the arrow. The spool has now been moved to a position in which the abutment member 166 is seated against the end plug 160. The valve land 163 is thereby moved to a position between the ports 167 and 170 and the valve land 164 between the ports 168 and 171.

From the foregoing, it will be observed that the lands are so spaced as to be positioned either covering certain ports or located between them. Also, the abutment members on the spool, when seated against an adjacent end plug, properly position the lands in relation to the ports, as shown and described.

With a shifting of the spool 158 to the right, as in Figure 13, duid under pressure from conduit 152 ows through the valve 153 into a conduit 187 to the clamp cylinder 105 (Figures l and 2) thereby advancing the piston 109 to close the wedge-shaped clamp 112 against the tubing 45 inserted through the tubing clamp structure 97. Fluid, within the cylinder ahead of the piston, flows through a conduit 188, through the directional valve 153, and through conduits 189 and 190 to the reservoir 150. Any uid trapped within the valve between the land 164 and the end plug 160 is drained through the port 171 and a conduit 191 to the drain conduit 190. When the piston 169 is fully advanced in the cylinder 105, the pressure in conduit 152 rises until it exceeds the pressure-setting of a sequence valve 192. The sequence valve then opens permitting fluid to low from the Ypressure conduit 152 through a conduit 193 to the tracer or follower valve-117 where it is available for operating the pusher cylinders.

As shown in Figures 14, 15 and 16, the valve 117 has a body 194 chambered as at 195 to slidingly receive a spool 196; The spool is provided with end guide lands 197 and 198 and intermediate valve lands 199 and 200. Unlike the valve lands previously described with the directional valve 153, the lands 199 and 200 have modied peripheral surfaces. The land 199 is provided with an intermediate cylindrical peripheral surface 201 flanked by tapered or conical shaped surfaces 202 and 203. Similarly, the land 200 has an intermediate cylindrical peripheral-surface 204 llanked by tapered or conical shaped surfaces 205 and 206. The tapered 'surfaces are provided to effect a more gradual opening and closing of the associated port, it being desirous in the valve 117 that the actuation of spool 196 be smooth.-

The chamber of the valve body is closed at one end by a threaded adjusting plug 207 and by a closure plug 208 at the other end. By threading the plug A207 within the chamber, adjustment is made in the tension ofa coiled spring 209 to normally locate the spool in an-offset position in which the guide land 198 is seated against the closure plug 208.

On one side of the valve body there is provided spaced ports 210 and 211 located intermediately with respect t opposed ports 212, 213 and 214. When the spool-is in an olset position, as shown in Figure 14, the valve land .199 is located between ports 210 and 213 and Vthe valve land 200'between the ports 211 and 214.

An actuating rod 215 extends from the end guide land 198 through an opening 216 in the closure plug 208. The tracing finger or sensing arm 11S is removably mounted onthe end:of.the.actuating rod and held in adjusted positionby asetscrewf 217. Any pressure exerted'against the arm 118 etfectsmovement of the-spool 196against Ythe coiled spring 209; The two positions to which-the spool is moved, from the olset position shown in Figure` 14, are illustratedinFigures l and 16.

In the olsef;position, uid under pressure from the conduit 193 ows through. the valve, the port 211, and a conduitr218 into"the:pusher cylinders SSand 86.- rljhe pistonsr 88fand`90are Athereby forced ahead'inoving both the tubingclamp vstructure 97 and the tubing 4 5 clamped therein by the wedge-shaped clamp 112. Fluid from the forward or rod ends of the cylinders ows through: a conduit'219, through the tracer valve 117, and into conduits 220 and 221 Vto return to the reservoir 150. Similarly, any fluid in the chamber between the spool lands 200 and 198 isdrained to the reservoir 150 through a conduit 222.4 Accordingly, in its normal offset position, the valve 117 'electsa forward movement of the clamped tubing 45 toward the bending die 33.

When pressure is applied to the tracer finger 118, the coilednspring1209 of the tracer valve 117`is depressed. Withthe valve spool 196 moved to a position shown in Figure 15, the valve lands are located over and mask the ports-210 and 211 thereby shutting olf the llow of fluid tothe conduits- 219 and 218, respectively. The valve `is thenin an inoperative or neutral condition. Withthe parts so positioned, any fluid trapped between an end land and its adjacent valve land is drained through conlnts 220 and 222.

Actually, the spool 196 of the tracer valve 117 is required to be shifted very slightly to effect the chan-ges necessary to actuate or stop the operation of the pusher cylinders as shown in Figures 14 and l5. The system, then, is extremely sensitive and any slight deflection in the `tracer linger or sensing arm 11S causes an 'immediate response-in the pusher cylinders.

With the system in partial Voperation as described, that ris with the clamp structure 97 'clamping the inserted tubing;and huid pressure available at the tracer.valve'117 i the pusher. cylinders. .pushing force exerted on the tubing forcing it toward the -to actuate the pusher cylinders fand 86, the bending mechanism is readyrfor operation.

The bending cylinder 141 is first caused to operate in a bending direction or with the piston 142 travelling to the right, as shown in Figure 1. Movement of the piston causes the driving chain 147 to start rotation of the sprocket which in turn starts a rotation of the bending die 33 in a clockwise direction. In this movement, the bending die and the clamping die unit 34 start a pulling of the tubing around theaxis of the bending die. Simultaneously, the control drum 82 rotates with the bending die thereby moving the endless tape 96 and the ag member 119adjustably carried thereon.

The tracer or follower-valve 117' and the adjustable flag member 119 are preset relative to each other. This is accomplished by moving the flag member along the tape and locking it at a desired. position to provide a space between-the flag member and the sensing arm 118. This space provides a lead for the movement of the'sensing arm to the ag member before the start of the bending operation andk results in placing the tubing under compression'and in a preloaded condition. The amount of preloading will, of course, depend upon such factors as the size of tubing, its wall thickness, and the type of metal therein.

Should the bending cylinder not be operative, then the sensing arm engages the ag memberl and the pressure exerted on it forces the spool to a position as shown in Figure l5 in which the valve 117"becomes inoperative.

vmove to draw .the nag-member 119 away from the sensing finger 118,.the. coiled spring 209 of the valve 117 shifts the spool forward to uncover the port 211 permitting uid toow .through the conduit 218 and actuate the pusher cylinders 85 and 86. Accordingly, sol long ias the flag member moves ahead of the sensing arm the pusher cylinders will be actuated. If the bending mechanismV stops, the stationary ag member causes the valve 117tobecome inoperativewhich stops Athe actuation of By this sensitive mechanism, the

bending die is controlled.

YThe operative relation of the respective mechanisms is such that suflicient pressure is developed by thel pusher cylinders to effect the same increment of movement of the tubing toward the bending die-as the distance traversed along the bend of the tubing at the outside thereof. This is accomplished by the control drum radius R1 being such as to locate the tape 96 at the same distance from thecenter of rotation of the bending die 33 as the outside `surface of the bend in the tubing (see Figure 3).

As the bend proceeds, the pusher cylinders continue toforce the tubing toward the bending die into the small working area tangent to the bending die. The metal in a uid state in this area is then drawn into the outside Wall of the tube bend as previously described. By constantly providing sufficient metal at the outside of the bend to avoid stretching, the originaLWall thickness of the tubing v in generally maintained throughout the length of such outside wall. Similarly, too much metal is provided at the Working area at the inside wall of the bend. This additional metal is evenly forced into` the inside Wall thereby increasing its thickness. Should the original thickness not be accurately maintained throughout the bend, the decrease would be negligible and of no consequence as the cold working of the metal during the bending operation introduces additional tensile strength in the outer wall.

inasmuch as the mechanism described herein practically -eliminates-any strain on the tubing as it is being bentylimitationsas tothe Ysharpness of bends previously experienced in tubebending machines are overcome than one segment in a mandrel tosupport'the outer wall f of the tube duringbending'is also eliminatedV since tension in the outer wall is reduced toa'minimum. All of these features provide fory easier bending particularly where the bends are close together.

When the bend is completed, operation of the bending cylinder is stopped and the spool ofthe directional valve 153 is shifted from the position Yshown in Figure 13 to that shown vin Figure 12. In the resulting relation of valve parts, iluid under pressure ows from the conduit 152 to the conduit 188 and into the cylinder 105. The piston 109, in moving to the rear end of the cylinder, withdraws the wedge-shaped clamp member 112 and releases the tubing 45 in the clamp structure 97. Any uid in the cylinder on the opposite side of the piston is drained away through the conduits 187, 191 and 190 back `to the reservoir 150. Similarly, any uid trapped between the guide land 163 and the end plug 159 is drained through the conduit 189.

As fluid again ows through the conduit 152 following a release of the static pressure required in maintaining clamp pressure on the tubing, the pressure in the line drops and the sequence valve 192 closes thereby shutting off the flow of uid through the conduit 193'to the tracer valve 117. For lack of pressure, the `valve 117 then becomes inoperative. This condition continues until the piston 109 is bottomed in the cylinder 105 at which time pressure in the conduit line 152 again builds up to exceed the setting of the sequence valve 192. When the sequence valve opens, fluid under pressure again ows through conduit 193 to the tracer valve 117. Inasmuch as the bending cycle was stopped, the ag member 119 is at rest and the abutting tracer finger has moved the spool of the tracer valve to the position shown in Figure rendering it inoperative.

To reverse the tracer valve and thereby eect a reverse operation of the pistons 88 and 90 in the pusher cylinders requires a manuel actuation of the tracer finger to move the spool to the position shown in Figure 16. Fluid from the pressure conduit 193 then ilows through the conduit 219 to etect a reversal of the pusher mechanism and a relief of the pushing force previously applied on the tubing during the bending cycle. Fluid in the cylinders on the opposite sides of the pistons drain through conduits 218, 222 and 221 to the reservior.

The clamp and pressure die cylinders are then actuated in a reverse direction to release the tubing from the bending die. The bent tubing is either removed to be replaced or reset at a new position for another bend. The bending cylinder is then actuated in a reverse direction to return the bending arm and the machine is again ready for a new bending cycle.

Modiiied forms of construction of the control mech-V anism are shown in Figures 18, l9, and 2l.

in Figure 18 is shown diagrammatically the bending die 33 and iclamping die 44 having been rotated to the completed bending position. The pressure die mechanism is of the same construction previouslyrdescribed except that the roller support 56a, carried on the frame 50a, is sui`n`ciently wider to carry a cylinder 225. The cylinder has'a piston 226 with a piston rod 227 connected to a cross-head 228.

interposed between the rollers 57, 58 and 59 and the tubing 45 is a pressure die 229 having a back plate por- Ytion 230, resting against the rollers, and a tube gripping portion 231. A boss 232 extends from the end of the back plate portion adjacent to the cross-head 228 and is xedly connected thereto. The cross-head also carries the tracer valve 117 against the nger or arm 118 of which the ag member 119 is adjusted on the tape 96. It is as desirable here as with the preferred form of conor arm 118.'

12 struction that the tubing 45 be pre-stressed before the actual bending takes place. Accordingly, the dag member 119`is adjusted in spaced relation to the sensing iinger It vvilljbeA noted inFigures 19 and 20, that the tube gripping portion 231 ofthe pressure die has a tube receiving groove 233, with a .serrated surface 234. The

Vpressure die mechanism is adjusted with suicient pressure to force the tube gripping portion tightly into contact with the tubing 45 to be bent.

As the bending die rotates, the tape 96 moving on the control drum 82 and the idler drum 95 draws the ag member 119 away from the tracer finger 118 thereby effecting an actuation of the cylinder 225 in the same manner as the pusher cylinders previously described. The piston is actuated so long as there is no deflection by inger 118. Should the Hag member slow down or stop, the deflection of the sensing arm 118 by abutment against the flag member would result in a. similar slowing down or stopping of the cylinders.

As the piston 226 is actuated to the rear end of the cylinder 225 it draws with it the cross-head 228 which in turn actuates the pressure die 229. The serrations 234 in the tubing grove, grip the tubing 45 and push it toward the bending die in much the same manner and for the same purposes as described in detail with the preferred form of construction.

Figure 21 illustrates another modified form `of control mechanism. In this form the bending die 33 and the clamping die 44 cooperate to draw the tubing around the rounded nose of the bending die to form a bend in the tubing. As previuosly described with the preferred form of construction, the control drum 82 and the idler drum carry an endless tape 96. Also, pusher cylinders 85 and 86 provide the pushing pressure through a cross-head 235 to force the tubing toward the bending die during the bending operation. The tracer or follower valve 117 is carried on one end of the cross-bar to position the nger 118 in line with the travel of the flag member 119.

A departure from the previously described mechanism is in the drive of a second tape 236 carrying the adjustable flag member 119. The idler drum 95 has a sprocket 237 which is operatively connected to a double sprocket 238 of a speed control device 239 by means of a driving chain 240. It is to be understood that it is Within the scope of this modified invention that drums and belts may be substituted for the described sprockets and chains. Another chain or belt 241 operatively connects the sprocket 238 and a sprocket 242. The speed control device is of well known construction so that details thereof are not shown or described. The relative speed of the drums or sprockets 238 and 242 may be varied as desired through an adjusting wheel 243. The tape 236, on which the ag member 119 is adjustably carried, operatively connects the drum 242 and a drum 244.

During the bending cycle the directions of movement of the various driving belts or chains are shown by arrows. When the ag member pulls away from the tracer finger 118 the tube pushing mechanism is made operative in theV same manner as previously described. Through the adjustable speed control 239, the speed of the belt or tape 236 may be varied to be greater or less than the rate at which the bend is formed. By this feature, an additional control is provided for determining the amount of metal made available at the tangent working area 79. It follows from what was said previously herein Y that the thickness of the tubing walls at the bend, parvnormally incident in the usual draw-bending operations.

In consequence, lighter parts may be provided thereby asm-,aaa

effecting a reduction in the manufacturing cost and increasing the life of the machine.

The bending control mechanisms previously described are operated in such amanner asto apply a pushing pressure on the tubing as it is being bent. This is for the particular purpose of controlling or eliminating any-tension and resulting stretching in the outer wall of the bend. As described, such auv operation elects an increase in compression in the inner wall of the bend. However, in many bendingoperations of tubingfthe compression in the inner wall results in wrinkling. This wrinkling usually is avoided byproviding a wiper die to engage the side of the tubing along which -the inside wall of the bend is formed. The wiper'die has-a long, forward lip extending along the tubing with its end positioned irnmediately adjacent the tangent of the curved nose of the bending die or its line of contact with the tubing. The support so provided permits a thickening of the inside wall at the bend without any wrinkling.

While the bend so described is structurally satisfactory, the difficulty of manufacturing and maintaining the wiper die makes the operation expensive. This excessive cost may be avoided where a bend is to be provided in which the radius is 'sufficient to effect a. maximum amount of inside Wall thickening without any wrinkling.l During the bending operation it is desired. that the normal travel A--B of the tubing (see Figure 17) be reduced to the point where the compression in the inside wall no longer forms wrinkling. This is accomplished by reversing or swinging the clamp structure '97 through an arc of 180. The wedge-shaped clamp member 112 is then operated in4 a direction toward the bending die. Ifk desired, a collet type chuck may be substituted for the wedge clamp member. The pusher cylinders 85 and 86 are connected to the clamp structure in a manner as previously shown. The power strokes of the pistons will continue toward the bending die but at a reduced rate controlled by the speed of movement of the ilag member away from the tracer valve.

The above described modifications have not vseparately been illustrated as they are simple mechanical changes.

This operation eliminates the need for any wiper die. As a result, the bending mechanism is a much more simple and inexpensive construction and the bends accomplished thereby are smooth and unwrinkled.

From the foregoing description, it is believed that the nature of the several forms of the invention and the manner in which each is carried out will readily be apparent to those skilled in this art. It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles f this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

l. In a tube bending machine, a rotatable bending die, a gripping means adapted to grip tubing to the die and turn with the die, a pressure die mechanism supporting tubing against pressure developed at the point of bending, a mandrel preventing the collapse of the tubing at said point of bending, valve means having a fluid control valve operable for the control of fluid llow therethrough, a clamp construction movable toward and away from said bending die and having a wedging member for gripping tubing in the clamp construction, a iirst cylinder and piston means responsive to said valve means for actuating said wedging member to grip the tubing, a tracer valve having a fluid control valve in normally operative position for the passage of uid therethrough and an arm for shifting said control valve to inoperative position, a carrier drum rotatable with said bending die, `an idler drum, a belt around said drums and movable therewith at a predetermined speed relative to the rotation of said bending die, an actuator adjustable along said belt and movable in the same path of movement as and ahead of said tracer `valve,'andasecond power cylinder and piston means normallyresponsive-to thefluid controlivalve for moving said clamp construction` and-clamped tubingv relativeto the bending die asit-rotate's.

2. Ina-tube bendingmachine, a rotatable bending die, a grippingmeans adapted to grip tubing to the die and turn Withrthe die, a pressure die' mechanism supporting tubing against pressure-developed at the point of bending, a mandrel preventing the collapseof the tubing at said point of bending, a fluid valve having Va spool shiftable to forward, closed and reverse positions for controlling the ilowzofL fluid: therethrough, a movable clamp construction havinga wedging member for clamping tubing therein, a clamp cylinder and pistons means responsive to said fluid valve for actuating the wedging member into `and out of clamping positions-,a tracer valve movable with said clamp construction and. havingv a spoolY shiftable to closed and reverse positions, a1 coiled spring'normally maintaining the spool in,.a.vvalveoperative.position .for the flow of A.fluid through. the valve, and `an actuating arm movable for shifting saidispool against the vcoiled `spring to the valve' closed and reverse positions,actuating means operatively connected.- toV vsaid bending. die for co-movement thercwithand; movable along the pathvof movement of the tracer valve actuating arm, andf power cylinder and piston vmeansresponsive:,to said. tracer valve for moving said clamp vconstruction.

3. Infa tube bending machine, a rotatable bending die, a gripping-means adapted. to grip tubing to the die and `turn with thedie, apressuredie mechanism supporting tubing against-pressure.developed at the point offbending,

mandrelfadapted'to be: positionedaxially within the tube toprevent the collapse of the tube at the point of ,bending,.a, tube,engag ing andv feeding means movable axially of the tube, said means securely engaging the tube to positively feed it axially toward the bending die, hydraulically operated means operating the tube engaging and feeding means, valve means for said hydraulically operated means carried by the tube engaging and feeding means, a control arm for said valve means and means actuated by the rotatable bending die for moving the control arm as the bending die rotates so that the control arm means is actuated in accordance with the speed of rotation of the die.

4. In a tube bending machine, a rotatable bending die, a gripping means adapted to grip tubing to the die and turn with the die, a pressure die mechanism supporting tubing against pressure developed at the point of bending, a mandrel adapted to be positioned axially within the tube to prevent the collapse of the tube at the point of bending, a tube engaging and feeding means movable axially of the tube, said means securely engaging the tube to positively feed it axially toward the bending die, hydraulically operated means operating the tube engaging and feeding means, valve means controlling the actuation of the hydraulic means and carried by the tube engaging and feeding means, a control member for said valve means, disposed in advance thereof and engageable with the valve means to render it inoperative and means actuated by the rotatable bending die for moving said control member in advance of the tube engaging and feeding means as the rotatable bending die is rotated so that the valve means is operative to permit the hydraulically operated means to advance the tube engaging and feeding means for feeding the tube toward the rotatable bending die in accordance with the rate of rotation of such die.

5. In a tube bending machine, a rotatable bending die, a gripping means adapted to grip tubing to the die and turn with the die, a pressure die mechanism supporting tubing against pressure developed at the point of bending, a mandrel adapted to be positioned axially within the tube to prevent the collapse of the tube at the point of bending, a tube engaging and feeding means movable axially of the tube, said means securely engaging the tube it inoperative and means actuated by the rotatable bending die for moving said control member away from and in advance of the control means as the rotatable bending die is rotated so that the control means is operative to operate the power operated means for feeding the tube toward the rotatable bending die in accordance with the rate of rotation of the rotatable bending die.

6. In a tube bending machine, a rotatable bending die, means rotating said die, a tube gripping means adapted to grip tubing to the die and turn with the die, a pressure die mechanism supporting the tubing against pressure developed at the point of bending, a mandrel adapted to be positioned axially within the tube to prevent the collapse of the tube at the point of bending, a tube engaging and feeding means movable axially of the tube, said means securely engaging the tube to positively feed it axially toward the bending die, a hydraulic cylinder means having a piston means, means connecting said piston means to the tube engaging and feeding means for moving the same toward and away from the bending die, valve means controlling the communication of the cylinder means with a source of uid pressure, said valve means being carried by the tube engaging and feeding means, a drum rotated by the rotatable die and disposed coaxially therewith, an idler pulley xedly located relative to the drum along the axial path of movement of the 16 tube, an endless flexible member entrained over the drum and pulley, a control arm adjustably carried by said exible member and disposed in advance of the tube engaging and feeding means and engageable with the valve means `to hold it in a neutral, inoperative position, said valve including means operable upon the disengagement of the control arm therefrom to actuate the valve to establish communication between the cylinder means l and the source of tluid pressure.

7.- A tube bending machine as claimed in claim 6, wherein said tube engaging and feeding means includes a clamp construction and hydraulically actuated means operating said clamp construction.

8. Artube bending machine as claimed in claim 6,

vwherein'said tube engaging and feeding means includes a wedging means, cylinder and piston means actuating the wedging means and valve means controlling the cylinder and piston means.

`References Cited in the le of this patent UNITED STATES PATENTS 652,808 Parker July 3, 1900 1,013,839 COX `lan. 2, 1912 1,105,914 Y Miller Aug. 4, 1914 2,068,890 Sassen Jan. 26, 1937 2,306,224 Parker Dec. 22, 1942 2,357,873 Bower Sept. 12, 1944 2,412,731 Hoffman Dec. 17, 1946 2,430,217k Eastes Nov. 4, 1947 FOREIGN PATENTS 1,025,958 France `lan. 2.8, 1953 

